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INTRODUCTION Electromagnetic navigation bronchoscopy (ENB) has been developed as a novel ancillary tool for the bronchoscopic diagnosis of pulmonary nodules. Despite successful navigation in 90% of patients, ENB diagnostic yield does not generally exceed 70%.

OBJECTIVEWe sought to determine whether the presence of a bronchus sign on CT conditions diagnostic yield of ENB, and might account for the discrepancy between successful navigation and diagnostic yield.

PATIENTS AND METHODSWe conducted a prospective single center study of ENB in 51 consecutive patients with pulmonary nodules. ENB was chosen as the least invasive diagnostic technique in patients with a high surgical risk, suspected metastatic disease, advanced stage disease, or those who demanded a pre-operative diagnosis prior to undergoing curative resection. We studied patient and technical variables which might condition diagnostic yield including ; size, etiology, location, distance to the pleural surface, and FDG uptake of a given nodule, the presence of a bronchus sign on CT, registration point divergence, and the minimum distance from the tip of the locatable guide to the nodule measured during the procedure.

RESULTSThe diagnostic yield of ENB was 67% (34/51). The sensitivity and specificity of ENB for malignancy in this study were 71 and 100% respectively. ENB was diagnostic in 30/38 (79%) patients with a bronchus sign on CT, but only in 4/13 (31%) with no discernible bronchus sign. Univariate analysis identified the bronchus sign (p=0.005) and nodule size (p=0.04) as statistically significant variables conditioning yield, but on multivariate analysis only the bronchus sign remained significant (OR: 7.6; 95% CI: 1.8-31.7). No procedure related complications were observed.

CONCLUSIONSENB diagnostic yield is highly dependent on the presence of a bronchus sign on CT.